1. Field of the Invention
The present invention relates to an ion generating device that generates ions in air by corona discharge.
2. Background Art
FIG. 8 shows an ion generating device that generates ions by corona discharge. The ion generating device includes an ion generating element 1 that generates ions, a high-voltage generating circuit section 2 that supplies a high voltage to the ion generating element 1, and a housing 3 that houses the ion generating element 1 and the high-voltage generating circuit section 2. An opening 4 is formed in a front surface of the housing 3, and the ion generating element 1 is mounted to the housing 3 at the opening 4. The high-voltage generating circuit section 2 is mounted in the housing 3.
The ion generating element 1 includes a discharge electrode 5 and an induction electrode 6. The discharge electrode 5 is a needle-like electrode, and positive and negative discharge electrodes 5 are mounted on the circuit board 7. The induction electrodes 6 are formed of a sheet metal having a hole, and placed to face and surround the positive and negative discharge electrodes 5, and mounted on the circuit board 7. There is a certain distance between a peripheral edge of the induction electrode 6 and the discharge electrode 5, and a discharge space is formed between the electrodes 5, 6.
The high-voltage generating circuit section 2 includes a high-voltage transformer 8, a connector 9 for power connection, a control circuit, and other electronic components, which are mounted on a control board 10. The control board 10 is inserted and held in the housing 3.
A discharge cover 11 is provided on the front surface of the housing 3 so as to cover the ion generating element 1. Ion emission ports 12 are formed in the discharge cover 11 so as to face the discharge electrodes 5. A seal member 13 surrounding the discharge cover 11 is provided. When the ion generating device is incorporated into an electrical device such as an air conditioner for use, the ion generating device is mounted to a duct, and the seal member 13 is sealed to a wall surface of the duct to prevent air leakage. In FIG. 8, reference numeral 14 denotes a securing foot for mounting.
If the high-voltage generating circuit section 2 applies a high voltage between the discharge electrode 5 and the induction electrode 6, corona discharge occurs at a tip of the discharge electrode 5, and one or both of positive and negative ions are generated. The generated ions are emitted from the emission ports 12 to an outside. Blowing air into the ion generating device diffuses the generated ions into air.
In the ion generating device, a high voltage is generated and applied to the electrodes, thereby generating electromagnetic noise. The electromagnetic noise affects surrounding electrical devices. For example, the electromagnetic noise disturbs TV images or generates noise in radio sound. To prevent such electromagnetic noise, measures have been taken such as to cover a high-voltage transformer with a metal cap (Patent Literature 1), to inject filled resin into a housing for insulation molding to insulation mold a high-voltage generating circuit section (Patent Literature 2), and to house a housing in a metal box integrally provided with an induction electrode (Patent Literature 3).